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Modeling the N2 expirogram obtained with a normal breath and with a forced maneuver
Author(s) -
Caucha Luis Jhony,
Cruz Julio Cesar,
Melendrez Jose Maria
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.723.5
Subject(s) - apex (geometry) , diffusion , forced convection , functional residual capacity , convection , residual volume , expiration , combined forced and natural convection , chemistry , lung volumes , lung , mechanics , anatomy , medicine , respiratory system , thermodynamics , physics , natural convection
We recently showed that the expired CO 2 , previously diluted in the alveoli, became more evident with the forced expiration and revealed the effect of alveolar CO 2 diffusion from RV to ERV (Caucha's et al. FASEB J. 24:1063.5, 2012). Now, we modified Caucha's model to simulate a N 2 expirogram, changing the number of Weibel's generations assigned for convection, convection‐diffusion and diffusion in the seven parallel regions from apex to base of the lung. The subject inhaled 1L of air from Functional Residual Capacity (FRC) and used 2.8s to exhale to FRC. The next breath, he inhaled 1L of 6.45% Ar, 72% N 2 in O 2 using 0.75s to inhale from FRC and exhaled to Residual Volume (RV) in 3.75s. The dotted lines are the experimental curves, and the ones obtained with the model, continuous lines, are shown in the Figure. The pulmonary blood flow was distributed exponentially from the 17 th to 23 rd generation; and the regional dead spaces were distributed with linear and exponential functions for the normal and force maneuver, respectively. While the number of generations for convection, convection‐diffusion and diffusion are constant for the seven parallel regions in a normal breath, in the force maneuver, the number of generations decreased for convection and increased for diffusion, from base to apex of the lung. In conclusion, the dilution of N 2 is produced more at the base than at the apical regions of the lung, as a consequence of the uneven regional volume distribution during inhalation and exhalation. Supported in part by CEIS (Centro de Enseñanza, Investigación y Servicios).